BACKGROUND In the applicant's International Application No.

PCT/AU01/00986 (WO02/14146), a cutting apparatus for removing debris from a propeller was described. The present invention relates to improvements to this invention.

Reference to this application is not an admission that its contents form part of the common general knowledge of the person skilled in the art.

Since the present invention incorporates improvements to the invention described in PCT/AU01/00986, the contents of this International Application are incorporated herein by reference. The invention described in this International Application will hereafter be referred to as the precursor invention.-- The precursor invention is applicable to marine vessels with inboard and outboard motors. However, in many outboard motors, very little space is provided between the boss of the propeller and the bulbous portion of the leg of the outboard motor often called the torpedo. It is not desirable to provide a long propeller shaft to space the propeller from the torpedo to fit a spool between the boss and the torpedo. One aspect of the present invention addresses this problem.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, there is provided a cutting apparatus for cutting debris from a propeller fixed to a propeller shaft comprising: a spool means for accumulating debris thereon, the spool means being fixed to the propeller shaft or the propeller so as to rotate with the propeller shaft and the propeller ; a blade oriented to cut debris that accumulates on the spool means; wherein the spool means is located between the blade and a circumferential surface of a boss of the propeller and the blade is located radially from the boss of the propeller; whereby when-said propeller rotates, debris snagged by the propeller is wound onto and accumulates on the spool means, whereupon debris is cut away by the blade.

According to another aspect of the present invention, there is provided a cutting apparatus for cutting debris from a propeller fixed to a propeller shaft driven by an outboard motor comprising: a spool means for accumulating debris thereon, the spool means being fixed to the propeller shaft or the propeller so as to rotate with the propeller shaft and the propeller; a blade coupled to a leg of the outboard motor oriented to cut debris that accumulates on the spool means ; whereby when said propeller rotates, debris snagged by the propeller is wound onto and accumulates on the spool means, whereupon debris is cut away by the blade.

In accordance with another aspect of the present invention, there is provided a cutting apparatus for cutting debris from a propeller fixed to a propeller shaft comprising:

a spool means for accumulating debris thereon, the spool means being fixed to the propeller shaft or the propeller so as to rotate with the propeller shaft and the propeller; a blade oriented to cut debris that accumulates on the spool means ; wherein a portion of the cutting edge of the blade is disposed at an acute angle to a surface of the spool over which the blade skims; whereby when said propeller rotates, debris snagged by the propeller is wound onto and accumulates on the spool means, whereupon debris is cut away by the blade.

According to yet another aspect of the present invention, there is provided a cutting apparatus for removing debris from a propeller fixed to a propeller shaft comprising: a spool means arranged to accumulate debris thereon and rotate with the propeller; a blade oriented to cut debris that accumulates on the spool means, the blade overlapping with a portion of the propeller; wherein the spool means includes a sacrificially wearable element positioned between the blade and the propeller; whereby when said propeller rotates debris snagged by the propeller is wound onto and accumulating on the spool means, whereupon debris is cut away by the blade.

Preferably the spool means is in the form of a ring mounted on the circumferential surface of the boss of the propeller.

Preferably the spool means has a flange for fitting within a recess or groove in a boss of the propeller. More preferably the recess is formed at a shoulder of the boss of the propeller. Preferably the spool means is fixed to the propeller by an interlocking overlap between an inwardly directed flange of the spool and the recess or groove of the

propeller.

Preferably the blade is coupled to a skeg of a leg of an outboard motor.

Preferably the spool means is in the form of a disc located between the boss of the propeller and a bearing through which passes the propeller shaft. The disc may overlap a portion of the boss of the propeller.

Preferably the spool means protects the propeller in a sacrificial manner from wear by or contact with the blade.

Preferably the spool means is a single piece annulus.

Alternatively the spool means is formed of a plurality of pieces that together form an annulus shaped spool.

Preferably the blade comprises a leading surface and a trailing surface disposed at an angle to the leading surface to form a cutting edge along a line of intersection of the surfaces. Preferably the leading surface is disposed at an angle relative to a line parallel with the axis of rotation of the propeller of between 0 and 45°. More preferably the angle is between 10° and 30°. Still more preferably the angle is about 22°.

Preferably the trailing edge is disposed at an angle relative to a line parallel with the axis of rotation of the propeller of between 45° and 90°. More preferably between 60° and 80° and still more preferably about 67°.

Preferably the leading surface is curved. Preferably the curve of the leading surface is a concave curve. Preferably the trailing surface is curved. Preferably the curve of the trailing surface is a concave curve.

Preferably a line bi-secting the leading and trailing

surfaces is disposed at an angle relative to a line parallel with the axis of rotation of the propeller of between 20° and 70°, more preferably 45°.

According to another aspect of the present invention there is provided a cutting apparatus for cutting debris from a propeller fixed to a propeller shaft comprising: a spool means for accumulating debris thereon, the spool means being fixed to the propeller shaft or the propeller so as to rotate with the propeller shaft and the propeller; a blade orientated to cut debris that accumulates on the spool means; wherein the blade comprises a leading surface and a trailing surface disposed at an angle to the leading surface to form a cutting edge along a line of intersection of the surfaces, wherein the leading surface is disposed at an angle relative to a line parallel with the axis of rotation of the propeller of between 0 and 45°, wherein the trailing surface is disposed at an angle relative to the line parallel with the axis of rotation of the propeller of between 0 and 90°.

Also according to the present invention, there is provided a propeller comprising a spool means arranged to accumulate debris thereon with rotation of the propeller for cutting away by a blade oriented to cut debris accumulated on the spool means.

In accordance with another aspect of the present invention, there is provided a spool for coupling to a propeller shaft or propeller so as to rotate with the propeller shaft and the propeller, the spool arranged to accumulate debris thereon, in use, for cutting away by a blade oriented to cut debris that accumulates on the spool.

In accordance with another aspect of the present invention,

there is provided a cutter for cutting debris from a propeller comprising a cutting edge, in use oriented to cut debris that accumulates on a spool means fixed to a propeller shaft or propeller so as to rotate with a propeller shaft and propeller, whereby when said propeller rotates debris snagged by the propeller is wound onto and accumulates on the spool means whereupon the debris is cut away by the cutter.

In the claims which follow and in the preceding description of the invention, . except where the context requires otherwise due to express language or necessary implication, the word"comprise"or variations such as"comprises"or "comprising"is used in an inclusive sense, i. e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Throughout this specification the term"outboard motor"is intended to mean a true outboard motor or other types of outboard motor commonly referred to as"stern drive outboard","Z-drive"or"inboard/outboard"motor.

Furthermore, in the art the term"outboard motor"is used to refer not only to the engine, but also the unit comprising the engine, a leg extending from the engine to below the waterline which houses the drive mechanism and a propeller.

In particular in the present invention is concerned more with the leg housing, the drive mechanism therein and the propeller than the engine. Throughout this specification the term"outboard motor"is intended to comprise the leg, the drive mechanism and the propeller.

DESCRIPTION OF DRAWINGS In order to provide a better understanding of the present invention, preferred embodiments will now be described, by

way of example only, with reference to the accompanying drawings, in which: Figure 1A is a cross-sectional plan view through A-A of Figure 2 of a lower portion of an outboard motor with one embodiment of a cutting apparatus in accordance with the present invention fitted to the outboard motor; Figure 1B is a side view of the cutting apparatus of Figure 1A ; Figure 2A is a cross-sectional plan view through B-B of Figure 2B of a lower portion of an outboard motor with an alternative embodiment of a cutting apparatus in accordance with the present invention; Figure 2B is a side view of the cutting apparatus of Figure 2A ; Figure 3 is a cross-sectional side elevation of a cutting apparatus including an alternative embodiment of a spool according to the present invention ; Figure 4 is a cross-sectional side elevation showing an further alternative embodiment of the spool according to the present invention ; Figure 5 in a cross-sectional side elevation of a cutting apparatus with an alternative embodiment of a cutter in accordance with the present invention ; Figure 6 is a cross-sectional plan view showing yet another alternative embodiment of the cutter according to the present invention ; Figure 7 is a cross-sectional plan view showing variations in the positioning of cutting apparatus in accordance with

the present invention ; Figure 8 is a cross-sectional plan view with three sets of cutting apparatus in different positions on a leg of the outboard motor; Figure 9 is a close up plan view of a cutting apparatus in accordance with the present invention in use ; and Figure 10 is an enlarged view showing detail of an embodiment of a cutting head according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Figures 1A and 1B, a typical lower portion of an outboard motor is shown, which includes a portion of a leg 20 that extends down from an engine (not shown) and houses a drive mechanism (not shown) for rotating a propeller shaft 15 under the power of the engine. The drive mechanism includes the propeller shaft 15 which extends from a torpedo shaped'portion 18 of the leg 20. The propeller shaft 15 is connected to propeller 16 in the conventional manner. The term"leg"is intended to mean the portion of an outboard motor extending between the engine housing and the propeller.

A preferred form of cutting apparatus 10 of the present invention includes a spool 12 fixed to the propeller 16 so as to rotate with the propeller 16 and a cutter 14 is mounted on the leg 20.

The propeller 16 includes a boss 25 between the propeller blades 13 and the torpedo 18. The boss 25 of the propeller 16 includes a step 38 before end surface 24. The rear 26 of the torpedo 18 and the surface 24 are spaced apart to define a gap 28 therebetween. Gap 28 may be so narrow that it is

not practical to insert a spool therebetween, thus the spool 12 sits within the step 38, and is in the form of a ring.

The cutter'14 comprises cutting head 31 and a mount 33. A blade 29 of the cutting head 31 has a cutting edge 32 for cutting debris on the spool 12. A circumferential surface of the spool 12 rotates underneath the head 31. The under side of the cutter 14 and in particular the head 31 of the cutter is situated very close to the surface of the spool 12. The head 31 of the cutter may be moveable with respect to its mount 33. In this case, upon installation or movement (adjustment) of the head 31, the blade 29 and/or other parts of the head 31 may make contact with the surface 35 of the spool 12 and with the first few revolutions of the propeller (and spool), the head 31 may shave away a thin layer of the surface 35 of the spool 12.

Because the blade is positioned very close to the surface of the spool 12, without the spool, the cutter runs the risk of damaging the boss 25 of the propeller 16. If any vibrations or bearing wear cause the cutter 14 to make contact with the spool 12, the spool 12 sacrificially protects the propeller 16 from damage by the cutter 14, whilst still acting to accumulate debris which is then cut away by the blade 29.

In Figure 1B, it can be seen that the cutter 14 may be positioned either above the torpedo 18 (in the case of 14A), or below the torpedo 18 (in the case of 14B). In the case of cutter 14B, the cutter 14 is mounted to a skeg or fin 21 of the leg 20. The mount 33 fixes the cutter to the leg 20 in a manner that positions the cutting edge 32A or 32B over the spool 12. The mount 33 may be integrally formed as part of the leg 20 of the outboard motor as shown in Figures 1A and 1B or it may be an after-market add-on as shown in Figures 2A and 2B.

In Figures 2A and 2B, the mount 33 of the cutter 14

comprises two spaced apart members 60 that collectively form a V shape, which are positioned on either side of the fin 21 and secured in place with bolts 62.

Referring to Figure 3, the spool 12 in this embodiment is in the form of a disc having a flange 36 that mates with and is nestled within a step 38 of the boss 25 of the propeller 16.

The disc has a hole in its centre to allow the propeller shaft 15 to pass therethrough. A surface of the spool 12 abuts a surface 24 of the boss 25 of the propeller 16.

Another surface 23 of the spool 12 is spaced from surface 26 of a bearing/carrier 70 in the case of an inboard motor or the torpedo 18 in the case of an outboard motor. The flange 36 provides enough surface area 35 over which the head 31 of cutter 14 can be radially positioned.

The spool 12 may be a single piece annulus affixed to the boss 25 of the propeller 16, by for example, bolting it in place. Alternatively, it may be formed of a plurality of pieces that connect together to form the annulus shaped spool 12. The spool 12 may be fixed to the propeller 16 by an interlocking overlap between an inwardly directed flange of the spool 12 and a recess or groove in the boss of the propeller, such as indicated by 37. A further alternative means of fixing the spool to the boss of the propeller is to use an adhesive. Yet another means for fixing the spool to the boss include press fit, shrink fit or screwing.

Combinations of the above methods or other means of fixing may also be used.

In Figure 4, the boss 25 of the propeller 16 has a rounded curve 38'rather than a pronounced step. In this case, the flange 36'is contoured to sit on the surfaces 24 & 38'of the boss 25 of the propeller 16. The spool 12 has the appearance of a cap over the end of the boss 25.

In Figure 5, the spool 12 is in the form of a ring located

within a step 38 on the boss 25 of the propeller 16. In this instance the gap between the surface 26 of the torpedo and surface 24 of the boss 25 of the propeller 16 is so small that extending the spool into this gap is impractical.

Nevertheless, the spool still performs the purpose of allowing debris to be wound around it (and the remainder of the propeller) and provides a protective surface between the cutter 14 and the propeller 16, with the spool 12 being worn or damaged in preference to the propeller or the cutter.

In this example the cutting edge 32 of the cutter 14 is sloped at an acute angle to the surface 35. This can provide an advantage by assisting the direction debris towards the spool 12 so that it is wrapped tight and accumulates, thereby forcing it onto the cutting edge 32 where it is then cut away by the cutting edge 32 of the cutter 14.

Referring to Figure 6, another embodiment of the cutter 14 is shown. In this embodiment the cutter head 31 and mount are integrally formed. The cutter mount includes lobes 84 that locate on either side of the rear end 80 of the leg 20.

A bolt 84 secures the cutter 14 to the leg 20. Blades 29 are indicated in directions to enable debris to be cut from the spool 12 no matter the direction of rotation of the propeller 16. As can be seen in other embodiments of the cutter 14 the oppositely directed blades 29 are common to most embodiments of the cutter, however the cutter may be provided with a single blade even though the two are preferred.

Fixing the cutter 14 to the rear 80 of the leg 20 is desirable as it reduces hydrodynamic resistance.

Conveniently in modern outboard motors an existing bolt is located in the rear 80 of the leg which may be removed and replaced with bolt 82 when a cutter 14 is mounted in position.

Referring to Figure 7, in this instance cutters 14''are coupled to either side of the torpedo 18. In the diagram it is shown as an after-market add-on, although it may be integrally cast into the torpedo during manufacture. The ring version of the spool 12 appears in this embodiment.

In Figure 8, three cutters 14', 14'', 14'''are shown mounted to the leg 20 in various positions to cut debris that accumulates on the spool 12. It is expected that a single cutter would be sufficient, but two, three or more may be used. Different embodiments of cutter may be used in combination as depicted here. The cap version of the spool 12 appears in this embodiment.

Referring to Figure 9, the method of operation of the present invention is similar to that described in PCT/AU01/00986, however the present invention provides certain advantages. Here it can be seen that the distance between the torpedo/bearing/carrier 18/70 and the propeller 16 is considerably less. This is typical of an outboard motor but may also be applicable to an inboard motor. In this case, the spool 12 performs the function of allowing the debris, in this case rope 40, to accumulate thereon and on the boss 25 of the propeller 16, and also provides a protective layer between the blade 14 and the boss 25 of the propeller 16 which may lie beneath the spool 12.

Referring to Figure 10, an enlargement of the cutter 14 from Figure 6 is shown. Reference line x'forms part of a reference cross positioned at the tip of cutting edge 32.

Line x is parallel with the axis of rotation of the spool 12 and propeller 16. The blade 29 is substantially triangular in cross section with one side of the triangle being a leading surface 50 and a second side of the triangle being a trailing surface 52 when the rotation of the propeller and spool is down the page. Leading surface 50 is at an angle a

to reference line x. Trailing surface 52 is at angle R to reference line x and leading surface 50 is at an angle Q relative to trailing surface 52. Thus angle 0 will be equal to angle R minus angle a.

Reference line y also forms part of the reference cross.

The angle between reference lines x and y is 90°. Debris such as rope will typically not be precisely parallel with reference line y, but as seen in Figure 9 will be more or less in the same direction. The cutting edge 32 is forced into the debris 40 due to accumulation of the debris. The cutting edge 32 focuses pressure on the debris along a line which maximises the pressure on the debris. Due to the relative differences in the hardness of the blade 29 compared to the debris, the debris is severed under the focused pressure causing the cutting the action.

The angles a and R can be varied to produce improved cutting. When angle a is generally between 10° and 30° improved cutting results. Having an angle R between 60° and 80° also produces improved results. Also a blade with angle 0 of between 30° and 70° produces improved results. In Figure 1-0, angle a is about 22°,-an-gle-ß is-about 67°-It is also noted that surfaces 50 and 52 maybe curved. In Figure 10 surface 52 can be seen to have a slight concave curve. Surface 50 may also have a concave curve.

The angles affect the angle of attack of the blade into the debris. If the angle of attack is too flat the blade may skim over the debris. If it is too sharp the blade does not scoop into the debris and may result in the blade breaking or failing to penetrate which may cause a jam.

Modifications and variations may be made to the present invention without departing from the basic inventive

concept. Such modifications may include providing a removable cutting edge 32 in the form of a blade tip so that if the cutting edge becomes blunt it can be replaced.

Such modifications and variations are intended to fall within the scope of the present invention, the nature of which is to be determined from the foregoing description and appended claims.